Specifically, certain telecommunication operators offer, in addition to telecommunication services proper, additional services. In the case of a short message service, these additional services are hosted in servers of messaging services which communicate with the short message server or servers so as to render the services offered.
Furthermore, upon the implementation of a short message service, which consists in transmitting a short message from a sender terminal to an addressee terminal, the message travels via the short message server and remains stored there for as long as the addressee terminal has not received it. This storage may result either from the fact that the transmission of the message to the addressee occurs on each connection of the terminal or from a failure of the transmission, when the transmission of the message occurs automatically, immediately upon receipt of the message by the server.
There is provision for the messages to contain a field, entitled “validity period” or “VP” which is used to define a maximum duration for which the message may be stored in the server. Thus, on expiry of this period of validity, if it has not been possible to transmit the short message to its addressee, it is deleted and the transmission attempts are stopped. Conversely, when a message is transmitted to its addressee, the message is destroyed either after explicit deletion by the user, or automatically after reading of the message, this being the case, for example, for welcome messages addressed to users by operators on a trip abroad. On the other hand, no provision is made to assign a duration of validity to the message after its receipt so as to prevent consultation thereof on expiry of the duration of validity. Hence, no provision is made to allow the use of a message, that is to say to read it, to reply to it, to record data stored therein, etc., for a limited period of time.